Methods for scanning an examination object by way of a CT system are generally known. In this case circular scans, sequential circular scans with feed, or spiral scans are used for example. With the scans, absorption data or, as the case may be, projections of the examination object are recorded from different recording angles with the aid of at least one X-ray source and at least one oppositely disposed detector, and said thus collected measured data is computed by way of appropriate reconstruction methods into sectional images (slices) through the examination object.
The detectors which serve to capture the measured data are an important component of the CT systems. The rotation of the radiation source around the examination object is subdivided into a multiplicity of succeeding measurement intervals. In order to provide the synchronization of the X-ray detectors that is required for X-ray CT systems, a synchronization input is usually provided on the X-ray detector, the arrival of a sync signal marking the end of the previous and the start of the next measurement interval. The average intensity of the sensor signal between two succeeding sync signals provides a measure for the signal that is subsequently read out. It is important for the image reconstruction that the measured data can be assigned to the respective angular position of its acquisition, i.e. the angular position must be known or be deducible for each measurement interval.